A parking assist apparatus, which can reduce an operational burden on a driver of a vehicle when parking the vehicle, is disclosed in JP2001-334898A (hereinafter, referred to as reference 1) and specifically in paragraphs 24 to 35, FIGS. 6 to 8, for example. According to the parking assist apparatus disclosed in the reference 1, a backward view of the vehicle is captured by a camera and displayed on a monitor screen provided inside a compartment of the vehicle. A guidance mark for parking the vehicle at a parking frame is displayed on the monitor screen.
A parking assist by the parking assist apparatus disclosed in the reference 1 is executed in accordance with a procedure as described herein. The driver stops the vehicle so that a front-rear direction of the vehicle is orientated substantially perpendicularly to a front-rear direction of a predetermined parking frame, to which the driver aims at parking the vehicle in a back-in parking manner. A stop position, at which the driver stops the vehicle, is a slightly forward position from a position where the driver can park the vehicle to the predetermined parking frame as a steering wheel is steered to a maximum steering angle. When a parking assist function is activated at the stop position, a parking stall, in which the vehicle can be parked in a case where the vehicle is reversed as the steering wheel is steered to the maximum angle, is superimposed and displayed on the monitor screen. The driver reverses the vehicle until the predetermined parking frame and the parking stall are matched and then stops the vehicle. A rear-end expected locus of the vehicle in accordance with an operation amount of a steering wheel is displayed on the monitor screen. The driver of the vehicle steers the steering wheel to an approximately maximum steering angle at the stop position of the vehicle. The rear-end expected locus of the vehicle extends towards the predetermined parking frame and nearly matches the predetermined parking frame on the monitor screen. The driver reverses the vehicle maintaining the steering angle of the steering wheel in accordance with an acoustic guidance. A vehicle width extended lines are superimposed and displayed on the monitor screen. Then, the driver reverses the vehicle maintaining the steering angle of the steering wheel until the vehicle width extended lines are orientated to be in parallel with the predetermined parking frame. When the vehicle width extended lines and the predetermined parking frame are arranged to be in parallel, the driver returns the steering wheel to a neutral position from the approximately maximum steering angle and reverses the vehicle in a straight manner so that the vehicle is parked within the predetermined parking frame.
The parking assist apparatus disclosed in the reference 1 has such a superior characteristic that a burden of a steering operation of the driver when parking the vehicle can be reduced. However, when the vehicle is orientated to be almost in parallel with the predetermined parking frame, the rear-end expected locus deviates from the predetermined parking frame. In a case where another vehicle is parked outside of the predetermined parking frame, the rear-end expected locus is superimposed and displayed on the parked vehicle on the monitor screen. The rear-end expected locus is an expected line of a condition where a current steering angle of the steering wheel is maintained. Accordingly, the driver's vehicle and the parked vehicle may not make contact one another directly. However, the driver may consider a possibility that his/her vehicle may make contact with the parked vehicle and therefore may returns the steering wheel from a steering angle to be maintained. Then, there is a possibility that the vehicle may not be parked within the parking frame and/or the vehicle is parked in an angled manner. It is preferable for the vehicle using the parking assist apparatus not to be parked in such an undesired manner.
A need thus exists for a parking assist apparatus which is not susceptible to the drawback mentioned above.